Pump apparatus

ABSTRACT

A pump apparatus includes a motor that rotates a shaft, and a pump that is driven by the shaft, suctions an oil, and delivers the oil to the motor. The pump apparatus includes a first flow channel to suction an oil into the pump through a suction port provided in a pump cover using a negative pressure in the pump, a second flow channel to deliver an oil to the inside of the motor through a delivery port provided in a pump body using pressurization of the pump, a third flow channel provided between a stator and a rotor, a fourth flow channel provided between the stator and a housing, and a fifth flow channel to discharge an oil inside the motor through a discharge port provided in the housing.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a U.S. national stage of PCT Application No. PCT/JP2018/006625,filed on Feb. 23, 2018, and priority under 35 U.S.C. § 119(a) and 35U.S.C. § 365(b) is claimed from Japanese Application No. 2017-040849,filed Mar. 3, 2017, the entire disclosures of each application beinghereby incorporated herein by reference.

1. FIELD OF THE INVENTION

The present invention relates to a pump apparatus.

2. BACKGROUND

Recently, electric oil pumps used for transmissions and the like havebeen required to have responsiveness. In order to realize responsivenessin an electric oil pump, there is a need to increase the output of amotor for an electric oil pump.

When a motor for an electric oil pump has a high output, a large currentflows in a coil of the motor, so that the temperature of the motorbecomes high, and a permanent magnet of the motor may be demagnetized,for example. Therefore, in order to curb temperature rise of the motor,there is a need to provide a cooling structure in the motor.

Japanese Patent Laid-open No. 2008-125235 discloses an electric motorincluding an oil supply mechanism in which a relative positionalrelationship between a stator and a rotor in an axial direction isdisplaced using an oil pressure of an oil according to a rotation speedof the rotor and the rotor is cooled by the oil.

However, in the electric motor disclosed in Japanese Patent Laid-openNo. 2008-125235, a stator and a rotor cannot be cooled at the same timeusing an oil.

SUMMARY

Example embodiments of the present invention provide pump apparatuseseach including a stator and a rotor that are cooled at the same time andachieves a high cooling effect without having degrading pump efficiency.

According to an example embodiment of the present disclosure, a pumpapparatus includes a motor including a shaft rotatably supported about acentral axis extending in an axial direction, and a pump on one side ofthe motor in the axial direction, is driven by the shaft extending fromthe motor, suctions an oil, and delivers the oil to the motor. The motorincludes a rotor rotating around the shaft, a stator disposed to facethe rotor, a housing accommodating the rotor and the stator, and adischarge port provided in the housing to discharge the oil. The pumpincludes a pump rotor attached to the shaft, a pump case accommodatingthe pump rotor, a suction port provided in the pump case to suction theoil, and a delivery port provided in the pump case to deliver the oil tothe motor. The suction port, the delivery port, and the discharge portare disposed at positions different from each other when viewed in theaxial direction. The pump apparatus includes a first flow channel tosuction the oil into the pump through the suction port of the pump usinga negative pressure in the pump, a second flow channel to deliver theoil to an inside of the motor through the delivery port of the pumpusing pressurization of the pump, a third flow channel provided betweenthe stator and the rotor, a fourth flow channel provided between thestator and the housing, and a fifth flow channel to discharge the oilinside the motor through the discharge port.

According to example embodiments of the present disclosure, it ispossible to provide pump apparatuses in each of which a stator and arotor are cooled at the same time and a structure achieves a highcooling effect without degrading pump efficiency.

The above and other elements, features, steps, characteristics andadvantages of the present disclosure will become more apparent from thefollowing detailed description of the example embodiments with referenceto the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view illustrating a pump apparatus accordingto a first example embodiment of the present disclosure.

FIG. 2 is a view of a pump body viewed from a front side in an axialdirection.

FIG. 3 is a view schematically illustrating a main portion of the pumpapparatus according to the first example embodiment of the presentdisclosure.

FIG. 4 is a top view of a stator in the first example embodiment of thepresent disclosure.

FIG. 5 is a view illustrating a modification example of a discharge portin the first example embodiment of the present disclosure.

FIG. 6 is a view illustrating a modification example of a second flowchannel and a fifth flow channel in the first example embodiment of thepresent disclosure.

FIG. 7 is a view illustrating another modification example of the secondflow channel and the fifth flow channel in the first example embodimentof the present disclosure.

FIG. 8 is a cross-sectional view illustrating a pump apparatus accordingto a second example embodiment of the present disclosure.

DETAILED DESCRIPTION

Hereinafter, with reference to the drawings, pump apparatuses accordingto example embodiments of the present invention will be described. Thescope of the present invention is not limited to the following exampleembodiments and can be arbitrarily changed within a range of thetechnical ideas of the present invention. In addition, in the followingdrawings, in order to facilitate the understanding of each constitution,there are cases where the scales, the numbers, or the like of respectivestructures differ from those of the actual structures.

In addition, in the drawings, an XYZ coordinate system is suitablyindicated as a three-dimensional orthogonal coordinate system. In theXYZ coordinate system, a Z-axis direction is a direction parallel to onedirection which is an axial direction of a central axis J illustrated inFIG. 1. An X-axis direction is a direction parallel to a lengthdirection of a bus bar assembly 60 illustrated in FIG. 1, that is, atraverse direction in FIG. 1. A Y-axis direction is a direction parallelto a width direction of the bus bar assembly 60, that is, a directionorthogonal to both the X-axis direction and the Z-axis direction.

In addition, in the following description, a positive side in the Z-axisdirection (positive Z-side) will be referred to as “a front side”, and anegative side in the Z-axis direction (negative Z-side) will be referredto as “a rear side”. The rear side and the front side are names simplyused for description and do not limit actual positional relationships ordirections. In addition, unless otherwise specified, the direction(Z-axis direction) parallel to the central axis J will be simplyreferred to as “an axial direction”. A radial direction about thecentral axis J will be simply referred to as “a radial direction”. Acircumferential direction about the central axis J, that is, a direction(θ-direction) around the central axis J will be simply referred to as “acircumferential direction”.

In this specification, the expression “extending in the axial direction”includes a case of extending in a direction inclined within a range ofless than 45° with respect to the axial direction, in addition to thecase of strictly extending in the axial direction (Z-axis direction). Inaddition, in this specification, the expression “extending in the radialdirection” includes a case of extending in a direction inclined within arange of less than 45° with respect to the radial direction, in additionto the case of strictly extending in the radial direction, that is, adirection perpendicular to the axial direction (Z-axis direction).

First Example Embodiment

FIG. 1 is a cross-sectional view illustrating a pump apparatus 10 of thepresent example embodiment.

The pump apparatus 10 of the present example embodiment has a shaft 41,a motor section 20, a housing 12, a cover 13, and a pump section 30. Theshaft 41 rotates about the central axis J extending in the axialdirection. The motor section 20 and the pump section 30 are providedside by side in the axial direction.

As illustrated in FIG. 1, the motor section 20 has the cover 13, a rotor40, a stator 50, a bearing 42, a control device 70, the bus bar assembly60, and a plurality of O-rings. The plurality of O-rings include atleast a rear O-ring 82.

The rotor 40 is fixed to an outer circumferential surface of the shaft41. The stator 50 is positioned on an outer side of the rotor 40 in theradial direction. That is, the motor section 20 is an inner rotor motor.The bearing 42 rotatably supports the shaft 41. The bearing 42 is heldby the bus bar assembly 60. The bus bar assembly 60 is connected to anexternal power source and supplies a current to the stator 50.

The housing 12 holds the motor section 20 and the pump section 30. Thehousing 12 is open on the rear side (negative Z-side), and an endportion of the bus bar assembly 60 on the front side (positive Z-side)is inserted into an opening portion of the housing 12. The cover 13 isfixed to the rear side of the housing 12. The cover 13 covers the rearside of the motor section 20. That is, the cover 13 covers at least apart of the bus bar assembly 60 on the rear side (negative Z-side) andis fixed to the housing 12. Hereinafter, there are cases where thehousing 12 will be referred to as a member including the cover 13.

The control device 70 is disposed between the bearing 42 and the cover13. The rear O-ring 82 is provided between the bus bar assembly 60 andthe cover 13. Hereinafter, each component will be described in detail.

<Housing>

As illustrated in FIG. 1, the housing 12 has a tubular shape. In moredetail, the housing 12 has a multi-stage cylindrical shape in which bothends about the central axis J are open. The material of the housing 12is a metal, for example. The housing 12 holds the motor section 20 andthe pump section 30. The housing 12 has a tube portion 14 and a housingside flange portion 15.

The housing side flange portion 15 extends outward in the radialdirection from an end portion of the tube portion 14 on the rear side.The tube portion 14 has a cylindrical shape about the central axis J.The tube portion 14 has a bus bar assembly insertion portion 21 a, astator holding portion 21 b, and a pump body holding portion 21 c in theaxial direction (Z-axis direction) from the rear side (negative Z-side)to the front side (positive Z-side) in this order.

The bus bar assembly insertion portion 21 a surrounds an end portion ofthe bus bar assembly 60 on the front side (positive Z-side) from theouter side of the central axis J in the radial direction. Each of thebus bar assembly insertion portion 21 a, the stator holding portion 21b, and the pump body holding portion 21 c has a concentricallycylindrical shape, and the diameters thereof become smaller in thisorder.

That is, the end portion of the bus bar assembly 60 on the front side ispositioned on the inner side of the housing 12. An outer surface of thestator 50, that is, an outer surface of a core back portion 51 (whichwill be described below) is fitted onto an inner surface of the statorholding portion 21 b. Accordingly, the stator 50 is held in the housing12. An outer circumferential surface of a pump body 31 is fixed to aninner circumferential surface of the pump body holding portion 21 c.

The housing 12 has a discharge port 12 b. The discharge port 12 bdischarges an oil, which has been delivered to the motor section 20 fromthe pump section 30, to the outside of the pump apparatus 10. In theexample illustrated in FIG. 1, the discharge port 12 b is provided on aside surface of the housing 12. In detail, the discharge port 12 b ispositioned in the tube portion 14 of the housing 12 and between one endof the stator 50 on a side opposite to the pump section in the axialdirection and a bottom portion of the housing 12. The bottom portion ofthe housing 12 is a rear end portion of the housing 12 and is a frontend portion of the control device 70 and the bus bar assembly 60.

That is, the discharge port 12 b is positioned on the side surface ofthe housing 12 and on the side in front of the control device 70 and thebus bar assembly 60 in the axial direction. The position of thedischarge port 12 b is not limited to the position illustrated inFIG. 1. The discharge port 12 b may be provided at an arbitrary positionin the housing 12 and may be provided in the bottom portion of thehousing 12, for example.

In the present example embodiment, a control device and a bus barassembly are disposed in the bottom portion of the housing 12. However,disposition of the control device and the bus bar assembly is notlimited thereto. For example, they may be attached to a side surface ofthe motor section 20 or the like. In this case, a lid portion 22 b ofthe cover 13 becomes the bottom portion of the housing, and a tubularportion 22 a of the cover 13 is included on the side surface of thehousing.

An optimal position can be selected as the position of the dischargeport 12 b in accordance with the position of the pump apparatus 10inside an external apparatus to which the pump apparatus 10 is attached.For example, in the present example embodiment, it is conceivable thatthe pump apparatus 10 be attached to a continuously variabletransmission (CVT) while being disposed as follows. When the pumpapparatus 10 is disposed such that the axial direction extendshorizontally, and when the pump apparatus 10 is disposed such that thenegative side in the X-axis direction (negative X-side) becomes theupper side and the positive side in the X-axis direction (positiveX-side) becomes the lower side with respect to the shaft 41, thedischarge port 12 b may be provided at a position above the shaft 41 ina direction of gravity.

That is, when the pump apparatus 10 is disposed such that the directionof gravity becomes a positive X-direction in FIG. 1, and when thenegative X-side becomes the upper side and the positive X-side becomesthe lower side with respect to the shaft 41, the discharge port may beprovided at a position symmetrical about the shaft 41 with respect tothe discharge port 12 b illustrated in FIG. 1. The discharge port 12 bis provided on the upper side in the direction of gravity in this mannerdue to the following reason. Inside the motor section 20, an oil warmedby absorbing heat of the rotor 40 and the stator 50 is likely to bebiased upward in the direction of gravity, and a cold oil is likely tobe biased downward in the direction of gravity. Therefore, a hot oil canbe discharged from the motor section 20 with priority by providing thedischarge port 12 b on the upper side in the direction of gravity.

In the present example embodiment, an oil which has been suctioned intothe pump apparatus 10 through a suction port 32 c of the pump section 30is delivered to the inside of the motor section 20 from a delivery port31 c and is discharged to the CVT (external apparatus) through thedischarge port 12 b of the motor section 20. When the pump apparatus 10is attached to the CVT, the pump apparatus 10 is built inside atransmission case (not illustrated), for example. The transmission casehas a discharge port (not illustrated), and an oil which has beendischarged through the discharge port 12 b of the pump apparatus 10 isdischarged to the CVT via the discharge port of the transmission case.

The number of discharge ports 12 b to be provided is not limited to one,and a plurality of discharge ports 12 b may be provided. When aplurality of discharge ports 12 b are provided, each of the dischargeports 12 b may be provided at an arbitrary position on the side surfaceor in the bottom portion of the housing 12 as described above. Inaddition, a plurality of discharge ports 12 b may be provided on boththe side surface and the bottom portion of the housing 12. An oil insidethe motor section 20 can be more efficiently discharged by providing aplurality of discharge ports 12 b.

<Rotor>

The rotor 40 has a rotor core 43 and a rotor magnet 44. The rotor core43 surrounds the shaft 41 in a direction around an axis (θ-direction)and is fixed to the shaft 41. The rotor magnet 44 is fixed to the outersurface in a direction around the axis of the rotor core 43. The rotorcore 43 and the rotor magnet 44 rotate integrally with the shaft 41.

<Stator>

The stator 50 surrounds the rotor 40 in the direction around the axis(θ-direction) and rotates the rotor 40 around the central axis J. Thestator 50 has the core back portion 51, teeth portions 52, coils 53, andinsulators (bobbins) 54. The shape of the core back portion 51 is aconcentrically cylindrical shape with respect to the shaft 41.

The teeth portions 52 extend toward the shaft 41 from the inner surfaceof the core back portion 51. A plurality of teeth portions 52 areprovided to be disposed at equal intervals in the circumferentialdirection of the inner surface of the core back portion 51 (FIG. 4). Thecoil 53 is constituted of a wound conductive wire 53 a. The coil 53 isprovided in the insulator (bobbin) 54. The insulator (bobbin) 54 ismounted in each teeth portion 52.

<Bearing>

The bearing 42 is disposed on the rear side (negative Z-side) of thestator 50. The bearing 42 is held by a bearing holding portion 65 of abus bar holder 61 (which will be described below). The bearing 42supports the shaft 41. The constitution of the bearing 42 is notparticularly limited, and any known bearing may be used.

<Control device>

The control device 70 controls driving of the motor section 20. Thecontrol device 70 has a circuit board (not illustrated), a rotationsensor (not illustrated), a sensor magnet holding member (notillustrated), and a sensor magnet 73. That is, the motor section 20 hasa circuit board, a rotation sensor, a sensor magnet holding member, andthe sensor magnet 73.

The circuit board outputs a motor drive signal. The position of thesensor magnet holding member is set when a hole at the center is fittedto a small diameter part of the end portion of the shaft 41 on the rearside (negative Z-side). The sensor magnet holding member can rotatetogether with the shaft 41. The sensor magnet 73 has a ring shape inwhich N poles and S poles are alternately disposed in thecircumferential direction. The sensor magnet 73 is fitted onto the outercircumferential surface of the sensor magnet holding member.

Accordingly, the sensor magnet 73 is held by the sensor magnet holdingmember and is disposed to be rotatable with the shaft 41 in a directionaround the axis (positive θ-direction) of the shaft 41 on the rear side(negative Z-side) of the bearing 42.

The rotation sensor is attached to the front surface of the circuitboard on the front side (positive Z-side) of the circuit board. Therotation sensor is provided at a position facing the sensor magnet 73 inthe axial direction (Z-axis direction). The rotation sensor detects achange in magnetic flux of the sensor magnet 73. The rotation sensor isa Hall IC or an MR sensor, for example. Specifically, when a Hall IC isused, three Hall ICs are provided.

<Cover>

The cover 13 is attached to the rear side (negative Z-side) of thehousing 12. The material of the cover 13 is a metal, for example. Thecover 13 has the tubular portion 22 a, the lid portion 22 b, and a coverside flange portion 24. The tubular portion 22 a is open on the frontside (positive Z-side).

The tubular portion 22 a surrounds the bus bar assembly 60, in moredetail, the end portion of the bus bar holder 61 on the rear side(negative Z-side) from the outer side of the central axis J in theradial direction. The tubular portion 22 a is coupled to the end portionof the bus bar assembly insertion portion 21 a on the rear side in thehousing 12 via the housing side flange portion 15 and the cover sideflange portion 24.

The lid portion 22 b is connected to the end portion of the tubularportion 22 a on the rear side. In the present example embodiment, thelid portion 22 b has a flat plate shape. The lid portion 22 b blocks theopening portion of the bus bar holder 61 on the rear side. The surfaceof the lid portion 22 b on the front side comes into contact with thewhole circumference of the rear O-ring 82. Accordingly, the cover 13indirectly comes into contact with the rear surface of a main bodyportion on the rear side of the bus bar holder 61 via the rear O-ring 82throughout the circumference around the opening portion of the bus barholder 61.

The cover side flange portion 24 extends outward in the radial directionfrom the end portion of the tubular portion 22 a on the front side. Thehousing 12 and the cover 13 are bonded to each other while the housingside flange portion 15 and the cover side flange portion 24 overlap eachother.

The external power source is connected to the motor section 20 via aconnector portion 63. The connected external power source iselectrically connected to a bus bar 91 and a wiring member 92 protrudingfrom the bottom surface of a power supply opening portion 63 a of theconnector portion 63. Accordingly, a drive current is supplied to thecoils 53 of the stator 50 and the rotation sensor via the bus bar 91 andthe wiring member 92. For example, a drive current supplied to the coils53 is controlled in accordance with the rotation position of the rotor40 measured by the rotation sensor. When a drive current is supplied tothe coils 53, a magnetic field is generated and the rotor 40 rotates dueto this magnetic field. In this manner, the motor section 20 obtains arotation driving force.

<Pump Section>

The pump section 30 is positioned on one side of the motor section 20 inthe axial direction, in detail, on the front side (positive Z-axisside). The pump section 30 is driven by the shaft 41 extending from themotor section 20. The pump section 30 has a pump case and a pump rotor35. The pump case has the pump body 31 and a pump cover 32. Hereinafter,the pump cover 32 and the pump body 31 will be referred to as the pumpcase.

The pump body 31 is fixed to the inside of the housing 12 on the frontside of the motor section 20. An O-ring 71 is attached to the pump body31. The O-ring 71 is provided between the outer circumferential surfaceof the pump body 31 and the inner circumferential surface of the housing12 in the radial direction. Accordingly, a space between the outercircumferential surface of the pump body 31 and the innercircumferential surface of the housing 12 in the radial direction issealed. The pump body 31 has a pump chamber 33 which is depressed to therear side (negative Z-side), that is, the other side in the axialdirection from the surface on the front side (positive Z-side), that is,one side in the axial direction and accommodates the pump rotor 35. Theshape of the pump chamber 33 viewed in the axial direction is a circularshape.

The pump body 31 is open at both ends in the axial direction to allowthe shaft 41 to pass therethrough and has a penetration hole 31 a inwhich an opening on the front side is open in the pump chamber 33. Anopening of the penetration hole 31 a on the rear side is open on themotor section 20 side. The penetration hole 31 a functions as a bearingmember which rotatably supports the shaft 41.

The pump body 31 has an exposed portion 36 which is positioned on theside in front of the housing 12 and is exposed to the outside of thehousing 12. The exposed portion 36 is a part of the end portion of thepump body 31 on the front side. The exposed portion 36 has a columnarshape extending in the axial direction. The exposed portion 36 overlapsthe pump chamber 33 in the radial direction. The pump section 30 is apositive-displacement pump which performs pressure-feeding of an oil byincreasing and decreasing the volume of a sealed space (oil chamber) andis a trochoid pump in the present example embodiment. Hereinafter, usingFIG. 2, details of the trochoid pump will be described.

FIG. 2 is a view of the pump body 31 viewed from the front side in theaxial direction.

The pump rotor 35 is attached to the shaft 41. In more detail, the pumprotor 35 is attached to the end portion of the shaft 41 on the frontside.

The pump rotor 35 has an inner rotor 37 which is attached to the shaft41, and an outer rotor 38 which surrounds the outer side of the innerrotor 37 in the radial direction. The inner rotor 37 has a ring shape.The inner rotor 37 is a gear having teeth on the outer surface in theradial direction. The inner rotor 37 is fixed to the shaft 41. In moredetail, the end portion of the shaft 41 on the front side ispress-fitted into the inner rotor 37. The inner rotor 37 rotatestogether with the shaft 41 in the direction around the axis(O-direction).

The outer rotor 38 has a ring shape surrounding the outer side of theinner rotor 37 in the radial direction. The outer rotor 38 is a gearhaving teeth on the inner surface in the radial direction. The outerrotor 38 is rotatably accommodated inside the pump chamber 33. An inneraccommodation chamber 39 accommodating the inner rotor 37 is formed inthe outer rotor 38, and the inner accommodation chamber 39 is formed tohave a star shape. The inner rotor 37 is rotatably accommodated in theinner accommodation chamber 39.

The number of inner teeth of the outer rotor 38 is set to be more thanthe number of outer teeth of the inner rotor 37. The inner rotor 37 andthe outer rotor 38 mesh with each other. When the inner rotor 37 isrotated by the shaft 41, the outer rotor 38 rotates in accordance withthe rotation of the inner rotor 37. That is, the pump rotor 35 rotatesdue to rotation of the shaft 41. In other words, the motor section 20and the pump section 30 have the same rotation axis. Accordingly, thepump apparatus 10 can be prevented from having an increased size in theaxial direction.

When the inner rotor 37 and the outer rotor 38 rotate, the volume of aspace formed between the inner rotor 37 and the outer rotor 38 changesin accordance with their rotation positions. The pump rotor 35 suctionsan oil through a suction port 74 by utilizing a volume change anddischarges the suctioned oil through a discharge port 75 by pressurizingthe oil. When the pump apparatus 10 is in operation, a region where thevolume decreases has a higher pressure than a region where the volumeincreases, that is, a region into which the oil is suctioned.

In the present example embodiment, in the space formed between the innerrotor 37 and the outer rotor 38, the region where the volume increasesis defined as a negative pressure region, and the region where thevolume decreases is defined as a pressurization region. An oil issuctioned into the region where the volume increases, and an oil isdischarged out from the region where the volume decreases. The pumprotor 35 can suction an oil through the suction port 32 c by utilizing avolume change and can discharge the suctioned oil through the deliveryport 31 c by pressurizing the oil.

The suction port 32 c is disposed on one side of the negative pressureregion of the pump rotor 35 in the axial direction. In addition, thedelivery port 31 c is disposed on the other side of the pressurizationregion of the pump rotor 35 in the axial direction. Here, an oil whichhas been suctioned into the pump chamber 33 through the suction port 32c is accommodated in a volume part between the inner rotor 37 and theouter rotor 38 and is sent to the delivery port 31 c side. Thereafter,the oil is delivered to the motor section 20 through the delivery port31 c.

The pump section 30 is not limited to a trochoid pump, and a pump of anytype may be adopted as long as the pump is a positive-displacement pumpperforming pressure-feeding of an oil by increasing and decreasing thevolume of the sealed space (oil chamber). For example, the pump section30 may be a vane pump. When the pump section 30 is a vane pump, acylindrical rotor (not illustrated) fixed to the shaft 41 isaccommodated in the pump chamber 33. The rotor (not illustrated) has aplurality of slots and vanes slidably mounted in the slots. The outercircumference of the rotor is disposed to be eccentric with respect tothe inner circumference of the pump chamber 33, so that acrescent-shaped space is generated between the pump chamber 33 and therotor.

The crescent-shaped space generated between the pump chamber 33 and therotor is divided into a plurality of regions by the slots mounted in therotor. When the rotor rotates and the vanes mounted in the slots moveforward and rearward, the volume of each region changes in accordancewith the rotation position. Similar to the case of a trochoid pump, anoil can be suctioned through a suction port (not illustrated) byutilizing a volume change and the suctioned oil can be dischargedthrough the discharge port (not illustrated) by pressurizing the oil. Ineach region formed between the rotor and the pump chamber 33, the regionwhere the volume increases is the negative pressure region and theregion where the volume decreases is the pressurization region.

Description returns to the pump section (FIG. 1). The pump cover 32 isattached to the front side of the pump body 31. The pump cover 32 has apump cover main body 32 a. The pump cover main body 32 a has a diskshape extending in the radial direction. The pump cover main body 32 ablocks the opening of the pump chamber 33 on the front side.

The pump section 30 has the suction port 32 c and the delivery port 31c. The suction port 32 c is provided in the pump cover 32. In detail,the suction port 32 c is open at both ends of the pump cover 32 in theaxial direction and has a cylindrical shape extending in the axialdirection. The opening portion of the suction port 32 c on the rear sideis connected to the negative pressure region of the pump chamber 33.Since an oil is suctioned through the suction port 32 c due to anegative pressure in the pump section 30, an oil can be efficientlysuctioned when the suction port 32 c is connected to the negativepressure region.

The position of the suction port 32 c is not limited to the positionillustrated in FIG. 1. The suction port 32 c may be provided at anarbitrary position in the pump cover 32 and may be provided in the pumpbody 31. An optimal position can be selected as the position of thesuction port 32 c in accordance with the position inside the externalapparatus to which the pump apparatus 10 is attached. For example, whenan oil pan (not illustrated) serving as a supply source of an oil is onthe pump cover 32 side, an oil can reach the suction port 32 c at theshortest distance without providing an unnecessary flow channel, byproviding the suction port 32 c at the position illustrated in FIG. 1.

In addition, for example, when the supply source of an oil is on theside surface of the pump apparatus 10, an oil can reach the suction port32 c at the shortest distance without providing an unnecessary flowchannel, by providing the suction port 32 c on the side surface of thepump body 31. In detail, the suction port 32 c can be easily connectedto the negative pressure region of the pump chamber 33 by providing thesuction port 32 c in the pump body 31, that is, a part constituting awall portion of the pump chamber. The wall portion of the pump chamberis a part of a cylindrical shape of the pump body 31 extending in theaxial direction.

The delivery port 31 c is provided in the pump body 31. In detail, thedelivery port 31 c is open at both ends of the pump body 31 in the axialdirection and has a cylindrical shape extending in the axial direction.The opening portion of the delivery port 31 c on the front side isprovided on a surface of the pump body 31 facing the pump cover 32 andis connected to the pressurization region of the pump chamber 33. Sincean oil which has been suctioned into the pump chamber 33 through thesuction port 32 c is delivered to the motor section 20 due topressurization of the pump section 30, an oil can be efficientlydelivered when the delivery port 31 c is connected to the pressurizationregion.

The position of the delivery port 31 c is not limited to the positionillustrated in FIG. 1. The delivery port 31 c may be provided at anarbitrary position in the pump body 31 as long as the delivery port 31 ccan be connected to the pressurization region of the pump chamber 33 atthe position. For example, when the pump apparatus 10 is disposed suchthat the axial direction extends horizontally, the delivery port 31 cmay be provided at a position below the shaft 41 in the direction ofgravity.

That is, when the pump apparatus 10 is disposed such that the directionof gravity becomes a negative X-direction in FIG. 1, and when thepositive X-side becomes the upper side and the negative X-side becomesthe lower side with respect to the shaft 41, the delivery port may beprovided at a position symmetrical about the shaft 41 with respect tothe delivery port 31 c illustrated in FIG. 1. The delivery port 31 c isprovided on the lower side in the direction of gravity in this mannerdue to the following reason. Inside the motor section 20, an oil warmedby absorbing heat of the rotor 40 and the stator 50 is likely to bebiased upward in the direction of gravity, and a cold oil is likely tobe biased downward in the direction of gravity. Therefore, a cold oilcan be delivered to the lower side of the motor section 20 with priorityby providing the delivery port 31 c on the lower side in the directionof gravity.

The suction port 32 c and the delivery port 31 c are disposed atpositions different from each other in the circumferential directionwith reference to the central axis J. The reason for this is that thepressurization region and the negative pressure region are present inthe positive-displacement pump at positions different from each other inthe circumferential direction. When the suction port 32 c and thedelivery port 31 c are disposed at positions different from each otherin the circumferential direction with reference to the central axis J,the suction port 32 c can be disposed on the negative pressure regionside and the delivery port 31 c can be disposed on the pressurizationregion side. Therefore, as described above, an oil can be efficientlysuctioned into the pump section 30 and can be delivered to the motorsection 20.

In addition, in FIG. 3, the suction port 32 c, the delivery port 31 c,and the discharge port 12 b are disposed at positions different fromeach other when viewed in the axial direction of the pump apparatus 10.Moreover, a cross-sectional area of the delivery port 31 c is smallerthan a cross-sectional area of the discharge port 12 b. Thecross-sectional area of the delivery port 31 c indicates the openingarea at the narrowest place in the opening of the delivery port 31 cextending in the axial direction. Similarly, the cross-sectional area ofthe discharge port 12 b indicates the opening area at the narrowestplace in the opening of the discharge port 12 b extending in the axialdirection.

In pump apparatuses in the related art, an oil which had been suctionedfrom a pump section was pressurized to be discharged from the pumpsection. In contrast, in the pump apparatus 10 of the present exampleembodiment, an oil which has been suctioned from the pump section 30 ispressurized and is discharged thereafter via the inside of the motorsection 20. Here, an oil which has been discharged from the motorsection 20 requires a discharge pressure equivalent to that in the pumpapparatuses in the related art. Thus, the discharge pressure of an oilhas to predominate when being delivered to the motor section 20 from thepump section 30.

When the cross-sectional area of the delivery port 31 c is smaller thanthe cross-sectional area of the discharge port 12 b, a discharge lossincreases. However, the discharge pressure which has been generated inthe pump section till then can be maintained using a discharge pressurefrom the inside of the motor to the outside of the motor. That is, it ispossible to provide a structure in which the discharge pressure from theinside of the motor section 20 to the outside of the motor section 20 isnot degraded.

The cross-sectional area of the delivery port 31 c may be larger thanthe cross-sectional area of the discharge port 12 b. In this case, thedischarge pressure from the inside of the motor section 20 to theoutside of the motor section 20 can be further improved than thedischarge pressure from the pump section 30 to the inside of the motorsection 20.

Next, a cooling structure of the pump apparatus 10 according to thepresent example embodiment will be described. According to the presentexample embodiment, an oil which has been supplied to the pump chamber33 through the suction port 32 c of the pump section 30 is delivered tothe motor section 20 through the delivery port 31 c by the pump rotor35. The oil cools the stator 50 and the rotor 40 at the same time bycirculating inside the motor section 20 and is discharged to theexternal apparatus via the discharge port 12 b of the motor section 20.

FIG. 3 is a view schematically illustrating a main portion of the pumpapparatus 10 in order to facilitate the understanding of flow channelsfor an oil in the pump apparatus 10 illustrated in FIG. 1.

As illustrated in FIG. 3, the pump apparatus 10 has a first flow channel1 for suctioning an oil into the pump section 30 through the suctionport 32 c of the pump section 30 using a negative pressure in the pumpsection 30, a second flow channel 2 for delivering an oil to the insideof the motor section 20 through the delivery port 31 c of the pumpsection 30 using pressurization of the pump section 30, a third flowchannel 3 provided between the stator 50 and the rotor 40, a fourth flowchannel 4 provided between the stator 50 and the housing 12, and a fifthflow channel 5 for discharging an oil inside the motor section 20through the discharge port 12 b of the motor section 20. Hereinafter,details of each flow channel will be described.

<First Flow Channel>

The first flow channel 1 in FIG. 3 is provided in the pump cover 32 andleads to the inside of the pump section 30 through the suction port 32c. In detail, the suction port 32 c has a first opening portion 32 d inthe front end portion of the pump cover 32 and has a second openingportion 32 e near the negative pressure region of the pump chamber 33.The first flow channel 1 leads to the inside of the pump section 30 viathe first opening portion 32 d and the second opening portion 32 e ofthe suction port 32 c.

The position of the first flow channel 1 is not limited to the positionillustrated in FIG. 3 and is determined in accordance with the positionof the suction port 32 c. The position of the suction port 32 c can beprovided at an arbitrary position in the pump case as described above.For example, when the suction port 32 c penetrates the pump body 31 fromthe outer circumferential surface of the exposed portion 36 to a placenear the negative pressure region of the pump chamber 33, the first flowchannel 1 is provided in the pump body 31.

<Second Flow Channel>

The second flow channel 2 in FIG. 3 is provided in the pump body 31 andleads to the inside of the motor section 20 through the delivery port 31c. In detail, the delivery port 31 c has a first opening portion 31 d inthe front end portion of the pump body 31, that is, near thepressurization region of the pump chamber 33 and has a second openingportion 31 e in the rear end portion of the pump body 31.

The second flow channel leads to the inside of the motor section 20 viathe first opening portion 31 d and the second opening portion 31 e ofthe delivery port 31 c. An oil which has been suctioned into thenegative pressure region inside the pump section 30 from the first flowchannel is pressurized by the pump rotor 35 and flows to one end of thesecond flow channel on the front side, that is, the first openingportion 31 d of the delivery port 31 c from the pressurization regioninside the pump section 30.

<Third Flow Channel>

The third flow channel 3 in FIG. 3 is provided between the stator 50 andthe rotor 40. In the example illustrated in FIG. 3, the third flowchannel 3 is positioned between the inner circumferential surface of thestator 50 and the outer circumferential surface of the rotor 40. An oilwhich has flowed into the motor section 20 from the second flow channel2 flows to one end on the rear side from one end on the front side ofthe third flow channel 3.

The third flow channel 3 is not limited to a place between the innercircumferential surface of the stator 50 and the outer circumferentialsurface of the rotor 40. For example, as illustrated in FIG. 4, apenetration hole 51 b may be provided in the core back portion 51 of thestator 50, and the penetration hole 51 b may be used as the third flowchannel 3. In addition, a space between a plurality of teeth portions 52(between teeth adjacent to each other) disposed away from each other inthe core back portion 51 may be used as the third flow channel 3.

When the penetration hole 51 b of the core back portion 51 or a spacebetween the teeth portions 52 adjacent to each other is used as a flowchannel for an oil, the coils 53 of the stator 50 can be moreefficiently cooled and the rotor 40 can be cooled.

Similar to the stator 50, a penetration hole (not illustrated) or acut-out portion (not illustrated) may be provided in the rotor core 43,and the penetration hole or the cut-out portion may be used as the thirdflow channel 3. When the penetration hole or the cut-out portion of therotor core 43 is used as a flow channel, the rotor 40 can be moreefficiently cooled and the rotor magnet 44 can be prevented from beingdemagnetized. That is, the third flow channel 3 may be provided at anarbitrary position as long as the position is between the stator 50 andthe rotor 40.

<Fourth Flow Channel>

The fourth flow channel 4 in FIG. 3 is provided between the stator 50and the housing 12. In detail, the fourth flow channel 4 is providedbetween the outer circumferential surface of the stator 50 and the innercircumferential surface of the housing 12. When the pump apparatus 10has the fourth flow channel 4, an oil can more efficiently circulatebetween the pump section 30 and the motor section 20 and the motorsection 20 can be cooled with high efficiency.

The fourth flow channel 4 joins to the third flow channel 3 on the rearside and leads to the discharge port 12 b. An oil which has flowed intothe motor section 20 via the second flow channel 2 is divided into anoil flowing to the third flow channel 3 and an oil flowing to the fourthflow channel 4. The oil which has flowed to the fourth flow channel 4flows to one end on the rear side from one end on the front side of thefourth flow channel 4. Then, the oil which has flowed to the rear sidemerges with the oil from the third flow channel 3 and is discharged tothe outside of the pump apparatus 10 via the discharge port 12 b.

Since the surface area of the stator 50 which comes into contact with anoil can be increased by providing the fourth flow channel 4, the insideof the motor section 20 can be more efficiently cooled. Generally, coilsradiate the most heat in a motor. Heat radiated by the coils istransferred to the core back portion 51 and the teeth portions 52. Thatis, the stator 50 has a significant heat radiation quantity in the motorsection 20. Thus, if the stator 50 can be efficiently cooled, the motorsection 20 can be efficiently cooled.

As illustrated in FIG. 4, the fourth flow channel 4 may have a cut-outportion 51 a on the outer circumferential surface of the core backportion 51. In addition, the fourth flow channel 4 may have a cut-outportion 12 a on the inner circumferential surface of the housing 12. Thefourth flow channel 4 may have both or any one of the cut-out portion 51a and the cut-out portion 12 a.

When the stator 50 has the cut-out portion 51 a, the surface area of thestator 50 which comes into contact with an oil can be increased.Therefore, the inside of the motor section 20 can be more efficientlycooled. In addition, when the stator 50 has the cut-out portion 51 a, orwhen the housing 12 has the cut-out portion 12 a, the flow rate of anoil flowing to the fourth flow channel 4 can be increased. Therefore, anoil can more efficiently circulate.

<Fifth Flow Channel>

The fifth flow channel 5 in FIG. 3 is provided in the tube portion 14 ofthe housing 12 and leads to the outside of the pump apparatus 10 throughthe discharge port 12 b. The fifth flow channel 5 varies depending onthe position of the discharge port 12 b. The position of the dischargeport 12 b is not limited to the positions illustrated in FIGS. 1 and 3.As described above, the discharge port 12 b can be provided at anarbitrary position on the side surface of the housing 12 and in thebottom portion (cover 13) of the housing.

An example in which the discharge port 12 b is provided at anotherposition will be described below using FIG. 5. Oils which have flowedinto the third flow channel 3 and the fourth flow channel 4 individuallyflow to the rear side from the front side and are discharged from thefifth flow channel 5. In the present example embodiment, an oil whichhas been discharged to the outside of the pump apparatus 10 from thefifth flow channel is discharged to the CVT through the discharge portof the transmission case through the inside of the transmission case orthe like in which the pump apparatus 10 is built.

In the present example embodiment, the stator 50 is molded using aresin. That is, the stator 50 is an integrally molded product formed ofa resin 50 a. When the stator 50 is an integrally molded product formedof a resin, the surface area of the stator 50 which comes into contactwith an oil can be increased in the third flow channel 3 and the fourthflow channel 4 (which will be described below). Therefore, the inside ofthe motor section 20 can be more efficiently cooled.

Similar to the stator 50, the rotor 40 may be molded using a resin. Thatis, the rotor 40 may be an integrally molded product formed of a resin.When the rotor 40 is molded, the surface area of the rotor 40 whichcomes into contact with an oil can be increased in the third flowchannel 3. Therefore, the rotor magnet 44 can be prevented from beingdemagnetized and the motor can be more efficiently cooled.

According to the present example embodiment, the pump apparatus 10 hasthe motor section 20 that has the shaft 41 rotatably supported about thecentral axis J extending in the axial direction; and the pump section 30that is positioned on one side of the motor section 20 in the axialdirection, is driven by the shaft 41 extending from the motor section20, suctions an oil, and delivers the oil to the motor section 20. Themotor section 20 has the rotor 40 rotating around the shaft 41, thestator 50 disposed to face the rotor 40, the housing 12 accommodatingthe rotor 40 and the stator 50, and the discharge port 12 b provided inthe housing 12 to discharge an oil. The pump section 30 has the pumprotor 35 attached to the shaft 41, the pump case accommodating the pumprotor 35, the suction port 32 c provided in the pump case to suction anoil, and the delivery port 31 c provided in the pump case to deliver anoil to the motor section 20. In the pump apparatus 10, the suction port32 c, the delivery port 31 c, and the discharge port 12 b are disposedat positions different from each other when viewed in the axialdirection. The pump apparatus 10 has the first flow channel 1 forsuctioning an oil into the pump section 30 through the suction port 32 cof the pump section 30 using a negative pressure in the pump section 30,the second flow channel 2 for delivering an oil to the inside of themotor section 20 through the delivery port 31 c of the pump section 30using pressurization of the pump section 30, the third flow channel 3provided between the stator 50 and the rotor 40, the fourth flow channel4 provided between the stator 50 and the housing 12, and the fifth flowchannel 5 for discharging an oil inside the motor section 20 through thedischarge port 12 b.

According to the present example embodiment, an oil which has beensuctioned into the pump section 30 through the suction port 32 c due toa negative pressure in the pump section 30 and has been delivered to themotor section 20 through the delivery port 31 c due to pressurization ofthe pump section 30 flows inside the motor section 20 and cools thestator 50 and the rotor 40 at the same time. In the present exampleembodiment, an oil which has been suctioned into the pump section 30 isnot divided into an oil to be discharged to the external apparatus andan oil for cooling the motor section 20, and an oil which has beensuctioned into the pump section 30 is delivered to the motor section 20.Therefore, cooling of the stator 50 and the rotor 40 can be realized atthe same time without having the pump efficiency being degraded. Inaddition, according to the present example embodiment, in the pumpapparatus 10, the stator 50 can be cooled from both the housing 12 sideand the rotor 40 side by including the third flow channel 3 and thefourth flow channel 4. Therefore, the stator 50 can be efficientlycooled. That is, it is possible to provide a structure having a highcooling effect for curbing temperature rise in the motor section 20.

MODIFICATION EXAMPLE OF DISCHARGE PORT

In the example illustrated in FIG. 3, the discharge port 12 b ispositioned in the tube portion 14 of the housing 12, that is, on theside surface of the housing and between the rear end portion of thestator 50 and the rear end portion (bottom portion) of the housing 12.However, the position of the discharge port 12 b is not limited theretoand may be provided at an arbitrary position in the housing 12. Inaddition, the discharge port 12 b may be provided in the cover 13. As amodification example of the discharge port 12 b, a case where thedischarge port 12 b is provided in the bottom portion of the housing 12will be described below.

FIG. 5 is a view illustrating a case where the discharge port 12 b isprovided in the bottom portion of the housing 12.

In FIG. 5, different from the example illustrated in FIG. 1, the controldevice 70 is attached to a part other than the bottom portion of themotor section 20, for example, a side surface. In addition, in FIG. 5,the lid portion 22 b of the cover 13 becomes the bottom portion of thehousing, and the tubular portion 22 a of the cover 13 is included on theside surface of the housing.

The fifth flow channel 5 in FIG. 5 is a flow channel leading to theoutside of the pump apparatus 10 through the discharge port 12 b in thebottom portion of the housing 12. The first flow channel 1 to the fourthflow channel 4 are similar to those of the example illustrated in FIG.3. In the present modification example, oils which have flowed into thethird flow channel 3 and the fourth flow channel 4 individually flow tothe rear side from the front side and are discharged from the fifth flowchannel 5 illustrated in FIG. 5. In this manner, the discharge port 12 bcan be provided in the bottom portion of the housing 12, and the fifthflow channel 5 is determined in accordance with the position of thedischarge port 12 b. In the present modification example as well, thesuction port 32 c, the delivery port 31 c, and the discharge port 12 bare disposed at positions different from each other when viewed in theaxial direction of the pump apparatus 10.

As another flow channel, for example, the pump apparatus 10 may furtherhave a flow channel provided between the outer circumferential surfaceof the shaft 41 and the inner circumferential surface of the rotor 40.In addition, for example, a penetration hole (not illustrated) may beprovided in the rotor 40, and the penetration hole may be used as a flowchannel. An oil can more efficiently flow into the motor section 20 andthe motor section 20 can be cooled with high efficiency by includinganother flow channel in addition to the first flow channel 1 to thefifth flow channel 5.

MODIFICATION EXAMPLE OF SECOND FLOW CHANNEL

In the example illustrated in FIG. 3, the second flow channel 2 is aflow channel leading to the inside of the motor section 20 via the firstopening portion 31 d and the second opening portion 31 e of the deliveryport 31 c. However, a constitution having no delivery port 31 cillustrated in FIG. 3 can be employed. In this case, a clearance betweenthe shaft 41 and the pump body 31 in the axial direction is used as adelivery port.

In detail, as illustrated in FIG. 3, the pump body 31 is open at bothends in the axial direction to allow the shaft 41 to pass therethroughand has the penetration hole 31 a in which the opening on the front sideis open in the pump chamber 33. The penetration hole 31 a functions as abearing member which rotatably supports the shaft 41. Here, thepenetration hole 31 a provided in the pump body 31, that is, theclearance between the shaft 41 and the pump body 31 in the axialdirection is used as a delivery port. In this case, an oil which hasbeen suctioned into the pump section 30 passes through a space betweenthe shaft 41 and the pump body 31. That is, the second flow channel 2 ispositioned between the shaft 41 and the pump body 31.

When a space between the shaft 41 and the pump body 31 serves as thesecond flow channel 2, there is no need to separately provide thedelivery port 31 c, and it is easy to perform machining. In addition, anoil flowing from the pump section 30 can be used as a lubricant, and theoil can be efficiently delivered to the inside of the motor section 20.A cut-out portion may be provided on at least one of the outercircumferential surface of the shaft or the inner circumferentialsurface of the pump body 31. Accordingly, flow channel resistance isreduced when the second flow channel 2 passes through a space betweenthe shaft 41 and the pump body 31, and an oil can be more efficientlydelivered to the motor section 20 from the pump section 30.

In the present example embodiment, a case where the pump body 31 has aslide bearing structure has been described. However, for example, thepump body 31 may use any bearing as a bearing member. Hereinafter, acase where the pump body 31 has a bearing will be described using FIG.6.

In the example illustrated in FIG. 6, the shaft 41 is rotatablysupported in the direction around the central axis J by a first bearing34 and a second bearing 80. Similar to the case described above, an oilwhich has been suctioned into the pump section 30 can be delivered tothe motor section 20 by using the clearance between the shaft 41 and thepump body 31 in the axial direction as a delivery port. An oil which hasbeen suctioned into the pump section 30 passes through a space betweenthe shaft 41 and the pump body 31. In this case, the second flow channelpasses through a space between the pump body 31 and the shaft 41 and atleast any part of a second flow channel 2 a to a second flow channel 2c.

The second flow channel 2 a is positioned between the shaft 41 and thefirst bearing 34. The second flow channel 2 b is a flow channel passingthrough the inside of the first bearing 34. For example, when the firstbearing 34 is a ball bearing having a plurality of balls, the secondflow channel 2 b is positioned between balls adjacent to each other. Thesecond flow channel 2 c is positioned between the first bearing 34 andthe pump body 31.

Similar to the case of a slide bearing, in the second flow channels 2 ato 2 c, a cut-out portion or a penetration hole may be provided in atleast any of the first bearing 34, the pump body 31, and the shaft 41.Accordingly, flow channel resistance of the second flow channels 2 a to2 c is reduced, and an oil can be more efficiently delivered to themotor section 20 from the pump section 30.

In addition, the position of the first bearing 34 is not limited to theposition illustrated in FIG. 6. The first bearing 34 can be disposed atan arbitrary position between a front end surface and a rear end surfaceof the pump body 31. For example, in the example illustrated in FIG. 7,in the first bearing 34, the front end surface (pump side one end) ofthe first bearing 34 in the axial direction is on the rear side, thatis, the motor section side of the front end surface (pump side one end)of the pump body 31.

In the example illustrated in FIG. 6, the front end surface of the firstbearing 34 is at the same position as the front end surface of the pumpbody 31 in the axial direction. Therefore, an oil which has beendelivered to the motor section 20 from the pump section 30 flows in fromthe second flow channel 2 a, the second flow channel 2 b, and the secondflow channel 2 c and passes through the clearance between the shaft 41and the pump body 31 in the axial direction. In contrast, in the exampleillustrated in FIG. 7, an oil which has been delivered to the motorsection 20 from the pump section 30 in the second flow channel passesthrough the clearance between the shaft 41 and the pump body 31 in theaxial direction before reaching the first bearing 34.

Here, since the pump body 31 has a holding portion which directly holdsthe shaft 41, the clearance between the shaft 41 and the pump body 31 inthe axial direction is smaller than the clearance between the shaft 41and the pump body 31 in the axial direction illustrated in FIG. 6.Therefore, an oil can be prevented from being delivered to the motorsection 20 from the pump section 30, and degradation of the pumpefficiency can be prevented.

MODIFICATION EXAMPLE OF FIFTH FLOW CHANNEL

In the example illustrated in FIG. 3 or 5, the fifth flow channel 5 is aflow channel leading to the outside of the pump apparatus 10 through thedischarge port 12 b. However, a constitution having no discharge port 12b illustrated in FIG. 3 or 5 can be employed. In this case, a clearancebetween the shaft 41 and the housing 12 in the axial direction is usedas a discharge port.

In detail, as illustrated in FIG. 6, the shaft 41 is rotatably supportedin the direction around the central axis J by the first bearing 34 andthe second bearing 80. The second bearing 80 is held in the bottomportion of the housing 12. The rear end portion of the shaft 41penetrates the bottom portion of the housing 12 and protrudes to theoutside of the housing 12. Here, a penetration hole which is provided inthe housing 12 and is penetrated by the shaft, that is, the clearancebetween the shaft 41 and the housing 12 in the axial direction is usedas a discharge port.

In this case, an oil inside the motor section 20 passes through a spacebetween the shaft 41 and the housing 12. That is, the fifth flow channelpasses through a space between the shaft 41 and the housing 12 and atleast any part of a fifth flow channel 5 a to a fifth flow channel 5 c.In order to easily discharge an oil inside the motor section 20 byincreasing the clearance between the shaft 41 and the housing 12 in theaxial direction, for example, as illustrated in FIG. 7, a penetrationhole 12 c penetrated by the shaft 41 provided in the housing 12 may beincreased in diameter.

The fifth flow channel 5a is positioned between the shaft 41 and thesecond bearing 80. The fifth flow channel 5 b is a flow channel passingthrough the inside of the second bearing 80. For example, when thesecond bearing 80 is a ball bearing having a plurality of balls, thefifth flow channel 5 b is positioned between balls adjacent to eachother. The fifth flow channel 5 c is positioned between the secondbearing 80 and the housing 12.

Similar to the cases of the second flow channels 2 a to 2 c which aremodification examples of the second flow channel, in the fifth flowchannels 5 a to 5 c, a cut-out portion or a penetration hole may beprovided in at least any of the second bearing 80, a part of the housing12 holding the second bearing 80, and the shaft 41. Accordingly, flowchannel resistance of the fifth flow channels 5 a to 5 c is reduced, andan oil inside the motor section 20 portion can be more efficientlydischarged. In addition, in place of the second bearing 80, the motorsection 20 may have a slide bearing structure. In this case, the fifthflow channel is positioned between a bearing member (not illustrated)and the shaft 41.

[Second Example Embodiment]

Next, a pump apparatus according to a second example embodiment of thepresent invention will be described. In the first example embodiment,the motor section has a constitution of an inner rotor motor in which astator is positioned on the outer side of a rotor in the radialdirection. In contrast, a motor section in the present exampleembodiment has a constitution of an axial gap motor in which a stator isdisposed to face a rotor in the axial direction. Hereinafter, thedifference between the present example embodiment and the first exampleembodiment will be mainly described. In the pump apparatus according tothe present example embodiment, the same reference signs will be appliedto the same constitutions as the pump apparatus according to the firstexample embodiment, and description thereof will be omitted.

FIG. 8 is a cross-sectional view illustrating a pump apparatus 101 ofthe present example embodiment.

As illustrated in FIG. 8, the pump apparatus 101 has the shaft 41, amotor section 201, a housing 141, and a pump section 300. The motorsection 201 has the shaft 41 rotatably supported about the central axisJ extending in the axial direction. The motor section 201 and the pumpsection 300 are provided side by side in the axial direction.

The motor section 201 has a rotor 402, a stator 501, an upper bearingmember 421, a lower bearing member 422, a control device (notillustrated), a bus bar assembly (not illustrated), and a connector (notillustrated). The rotor 402 has a disk shape extending in the radialdirection. The rotor 402 has a plurality of magnets 442 which arearranged in the circumferential direction on a surface (positive Z-sidesurface) facing the stator 501, and a rotor yoke 432 which holds themagnets 442. That is, the magnets 442 is disposed to face the rear endportion of the stator 501 in the axial direction. The rotor yoke 432 isfixed to the outer circumferential surface of the shaft 41.

The upper bearing member 421 and the lower bearing member 422 rotatablysupport the shaft 41. The upper bearing member 421 and the lower bearingmember 422 are fixed to a bearing housing 630. The stator 501 has aplurality of cores which have a fan shape in a plan view and arearranged in the circumferential direction, coils which are provided inthe cores, and coil leader lines which lead from the coils of the cores.In addition, the stator 501 has a mold resin which firmly fixes theplurality of cores in an integrated manner, and a plurality of leaderline support portions which are provided at an outer circumferential endof the stator 501.

The housing 141 constitutes a casing of the motor section 201. Thecontrol device (not illustrated) and the bus bar assembly (notillustrated) may be accommodated on the rear side (negative Z-side) ofthe stator 501. The rotor 402 is accommodated on the rear side (negativeZ-side) of the stator 501. The housing 141 has a first housing 121 whichhas a covered cylindrical shape and of which the rear side is open, anda second housing (cover) 131 which has a bottomed cylindrical shape andis coupled to the rear side (negative Z-side) of the first housing 121.The material of the housing 141 is a metal or a resin, for example.

The first housing 121 has a top wall 121 a having a disk shape, and theshaft 41 passes through a central portion of the top wall 121 a. Thebearing housing 630 is fitted into the opening portion of the pumpsection 300 on the rear side. The bearing housing 630 holds the upperbearing member 421 and the lower bearing member 422.

The second housing 131 has a bottom wall 131 a which has a disk shape,and a cover cylinder portion 131 b which extends from a circumferentialedge portion of the bottom wall 131 a to the front side (positiveZ-side). The positions of the upper bearing member 421 and the lowerbearing member 422 are not limited to the positions illustrated in FIG.8 and can be changed. For example, the upper bearing member 421 may beincluded in the pump section 300 instead of the motor section 201.

The cover cylinder portion 131 b is fixed to the opening portion of thefirst housing 121 on the rear side (negative Z-side). In more detail,the first housing 121 and the second housing 131 are fixed by a methodsuch as bolt fastening using flange portions 111 and 112 of the secondhousing 131 and flange portions 113 and 114 of the first housing 121.

When the control device (not illustrated) and the bus bar assembly (notillustrated) are accommodated in the second housing 131, a penetrationhole (not illustrated) penetrating the bottom wall 131 a in the axialdirection is provided in the bottom wall 131 a of the second housing131, and a connector (not illustrated) is attached to the penetrationhole. An external connection terminal (not illustrated) penetrating thebottom wall 131 a from the bus bar assembly and extending to the rearside (negative Z-side) is disposed in the connector.

The housing 141 has a discharge port 131 c. The discharge port 131 cdischarges an oil, which has been suctioned by the pump section 300(which will be described below) through a suction port 321 c and hasbeen delivered to the motor section 201 through a delivery port 311 c,to the outside of the pump apparatus 101. In the example illustrated inFIG. 8, the discharge port 131 c is provided in the bottom portion ofthe housing 141. In detail, the discharge port 131 c is provided in thebottom wall 131 a of the second housing 131.

In addition, in the present example embodiment, the discharge port 131 cis positioned on the outer side of the stator 501 in the radialdirection when viewed in the axial direction. The reason is as follows.When the stator 501 is fixed to the shaft in the pump apparatus 101having a constitution of an axial gap motor, the following can berealized by including the discharge port 131 c at the position describedabove. That is, in the motor section 201, since an oil which has flowedto the third flow channel 3 is discharged at the shortest distancewithout passing through an unnecessary flow channel, an oil inside themotor section 201 can be efficiently discharged.

The position of the discharge port 131 c is not limited to the positionillustrated in FIG. 8. The discharge port 131 c may be provided at anarbitrary position in the housing 141. For example, the discharge port131 c may be provided on the side surface of the housing 141. Forexample, the discharge port 131 c may be provided between one end of thestator 501 on a side opposite to the pump section 300 in the axialdirection and the bottom wall 131 a of the second housing 131, in a tubeportion 121 b of the first housing 121 or the cover cylinder portion 131b of the second housing 131.

In addition, an optimal position can be selected as the position of thedischarge port 131 c in accordance with the position of the pumpapparatus 101 inside an external apparatus to which the pump apparatus101 is attached. For example, similar to the case of the first exampleembodiment, when the pump apparatus 101 is disposed such that the axialdirection extends horizontally, and when the pump apparatus 101 isdisposed such that the negative side in the X-axis direction (negativeX-side) becomes the upper side and the positive side in the X-axisdirection (positive X-side) becomes the lower side with respect to theshaft 41, the discharge port 131 c may be provided at a position abovethe shaft 41 in the direction of gravity.

That is, when the pump apparatus 101 is disposed such that the directionof gravity becomes the positive X-direction in FIG. 8, and when thenegative X-side becomes the upper side and the positive X-side becomesthe lower side with respect to the shaft 41, the discharge port 131 c isprovided at a position symmetrical about the shaft 41 with respect tothe discharge port 131 c illustrated in FIG. 8. The reason for this isthat a hot oil can be discharged from the motor section 201 withpriority by providing the discharge port 131 c on the upper side in thedirection of gravity.

In addition, the number of discharge ports 131 c to be provided is notlimited to one, and a plurality of discharge ports 131 c may beprovided. When a plurality of discharge ports 131 c are provided, eachof the discharge ports 131 c may be provided at an arbitrary position onthe side surface or in the bottom portion of the housing 141 asdescribed above. In addition, the discharge ports 131 c may beindividually provided on both the side surface and the bottom portion ofthe housing. An oil inside the motor section 201 can be more efficientlydischarged by providing a plurality of discharge ports 131 c.

The pump section 300 is positioned on one side of the motor section 201in the axial direction, in detail, on the front side (positive Z-axisside). The pump section 300 is driven by the motor section 201 and theshaft 41. The pump section 300 has a pump body 311, a pump rotor 351,and a pump cover 321. The pump rotor 351 has an inner rotor 371 and anouter rotor 381.

Similar to the first example embodiment, the pump section 300 is apositive-displacement pump and is a trochoid pump in the present exampleembodiment. The pump section 300 is not limited to a trochoid pump, anda pump of any type may be adopted as long as the pump is apositive-displacement pump. Since description for each member of thepump section 300 is similar to that in the first example embodiment, itwill be omitted. Since the structure of the pump section 300 is similarto that in the first example embodiment, description thereof will beomitted.

The pump section 300 has the suction port 321c and the delivery port 311c. Hereinafter, details of the suction port 321 c and the delivery port311 c will be described. The suction port 321 c is provided in the pumpcover 321. In detail, the suction port 321 c is open at both ends of thepump cover 321 in the axial direction and has a cylindrical shapeextending in the axial direction. The opening portion of the suctionport 321 c on the rear side is connected to the negative pressure regionof a pump chamber 331. Since an oil is suctioned through the suctionport 321 c due to a negative pressure in the pump section 300, an oilcan be efficiently suctioned when the suction port 321 c is connected tothe negative pressure region.

The position of the suction port 321 c is not limited to the positionillustrated in FIG. 8. The suction port 321 c may be provided at anarbitrary position in the pump cover 321 and may be provided in the pumpbody 311. Similar to the first example embodiment, an optimal positioncan be selected as the position of the suction port 321 c in accordancewith the position inside the external apparatus to which the pumpapparatus 101 is attached.

For example, the suction port 321 c may be provided in a side surfaceportion 321 a of the pump cover 321 in accordance with the position ofan oil pan (not illustrated) serving as a supply source of an oil. Whenthe suction port 321 c is provided in the side surface portion 321 a ofthe pump cover 321, the suction port 321 c is open in the pump cover 321and is open on the side surface of the pump body 311. In detail, thesuction port 321 c can be easily connected to the negative pressureregion of the pump chamber 331 by providing the suction port 321 c inthe wall portion of the pump body 311 and the side surface portion 321 aof the pump cover 321 circumscribing the wall portion.

The delivery port 311 c is provided in the pump body 311. In detail, thedelivery port 311 c is open at both ends of the pump body 311 in theaxial direction and has a cylindrical shape extending in the axialdirection. The opening portion of the delivery port 311 c on the frontside is provided on a surface of the pump body 311 facing a top wall 321b of the pump cover 321 and is connected to the pressurization region ofthe pump chamber 331. Since an oil which has been suctioned into thepump chamber 331 through the suction port 321 c is delivered to themotor section 201 due to pressurization of the pump section 300, an oilcan be efficiently delivered when the delivery port 311 c is connectedto the pressurization region.

In the present example embodiment, since the first housing 121 of themotor section 201 has the top wall 121 a, an opening portion is alsoprovided in a part connected to the opening portion of the delivery port311 c on the rear side in the top wall 121 a of the first housing 121.

The position of the delivery port 311 c is not limited to the positionillustrated in FIG. 8. The delivery port 311 c may be provided at anarbitrary position in the pump body 311 as long as the delivery port 311c can be connected to the pressurization region of the pump chamber 331at the position. For example, when the pump apparatus 101 is disposedsuch that the axial direction extends horizontally, the delivery port311 c may be provided at a position below the shaft 41 in the directionof gravity.

That is, when the pump apparatus 101 is disposed such that the directionof gravity becomes the negative X-direction FIG. 8, and when thepositive X-side becomes the upper side and the negative X-side becomesthe lower side with respect to the shaft 41, the delivery port 311 c isprovided at a position symmetrical about the shaft 41 with respect tothe delivery port 311 c illustrated in FIG. 8. The reason for this isthat a cold oil can be delivered to the motor section 201 with priorityby providing the delivery port 311 c on the lower side in the directionof gravity.

In the present example embodiment as well, the suction port 321 c andthe delivery port 311 c are disposed at positions different from eachother in the circumferential direction with reference to the centralaxis J. Accordingly, the suction port 321 c can be disposed on thenegative pressure region side and the delivery port 311 c can bedisposed on the pressurization region side. Therefore, as describedabove, an oil can be efficiently suctioned into the pump section 300 andcan be delivered to the motor section 201.

In addition, in FIG. 8, the suction port 321 c, the delivery port 311 c,and the discharge port 131 c are disposed at positions different fromeach other when viewed in the axial direction of the pump apparatus 101.Moreover, a cross-sectional area of the delivery port 311 c is smallerthan a cross-sectional area of the discharge port 131 c. Thecross-sectional area of the delivery port 311 c indicates the openingarea at the narrowest place in the opening of the delivery port 311 cextending in the axial direction. Similarly, the cross-sectional area ofthe discharge port 131 c indicates the opening area at the narrowestplace in the opening of the discharge port 131 c extending in the axialdirection.

The cross-sectional area of the delivery port 311 c may be larger thanthe cross-sectional area of the discharge port 131 c. In this case, thedischarge pressure from the inside of the motor section 201 to theoutside of the motor section 201 can be further improved than thedischarge pressure from the pump section 300 to the inside of the motorsection 201.

Next, a cooling structure of the pump apparatus 101 according to thepresent example embodiment will be described. In the present exampleembodiment, an oil which has been supplied to the pump chamber 331through the suction port 321 c of the pump section 300 is delivered tothe motor section 201 through the delivery port 311 c by the pump rotor351. The oil cools the stator 501 and the rotor 402 at the same time bycirculating inside the motor section 201 and is discharged to theexternal apparatus via the discharge port 131 c of the motor section201. Hereinafter, flow channels for an oil in the pump apparatus 101will be described mainly regarding the difference between the presentexample embodiment and the first example embodiment.

As illustrated in FIG. 8, the pump apparatus 101 has the first flowchannel 1 for suctioning an oil into the pump section 300 through thesuction port 321c of the pump section 300 using a negative pressure inthe pump section 300, the second flow channel 2 for delivering an oil tothe inside of the motor section 201 through the delivery port 311 c ofthe pump section 300 using pressurization of the pump section 300, thethird flow channel 3 provided between the stator 501 and the rotor 402,the fourth flow channel 4 provided between the stator 501 and thehousing 141, and the fifth flow channel 5 for discharging an oil insidethe motor section 201 through the discharge port 131 c of the motorsection 201. Hereinafter, details of each flow channel will bedescribed.

Since the first flow channel 1, the second flow channel 2, and thefourth flow channel 4 of the present example embodiment are similar tothose in the first example embodiment, description thereof will beomitted. The third flow channel 3 is positioned between the rear endsurface of the stator 501 in the axial direction and the front endsurface of the rotor 402 in the axial direction. In detail, an oil whichhas flowed into the motor section 201 via the second flow channel 2 isdivided into an oil flowing to the third flow channel 3 and an oilflowing to the fourth flow channel 4. An oil flowing into the third flowchannel passes through a space between the coils of the stator 501 firstand flows between the rear end surface of the stator 501 in the axialdirection and the front end surface of the rotor 402 in the axialdirection thereafter.

The oil which has flowed to the fourth flow channel 4 flows to one endon the rear side from one end on the front side of the fourth flowchannel 4. Since the surface area of the stator 501 which comes intocontact with an oil can be increased by providing the fourth flowchannel 4, the inside of the motor section 201 can be more efficientlycooled.

The fifth flow channel in FIG. 8 is provided in the bottom portion ofthe housing 141 and leads to the outside of the pump apparatus 101through the discharge port 131 c. The fifth flow channel 5 variesdepending on the position of the discharge port 131 c. The position ofthe discharge port 131 c is not limited to the position illustrated inFIG. 8. As described above, the discharge port 131 c can be provided atan arbitrary position on the side surface of the housing 141 and in thebottom portion of the housing 141.

An oil which has flowed to the fourth flow channel 4 merges with an oilfrom the third flow channel 3 and flows to the fifth flow channel 5. Inthe present example embodiment as well, an oil which has been dischargedto the outside of the pump apparatus 101 from the fifth flow channel 5is discharged to the CVT through the discharge port of the transmissioncase in which the pump apparatus 101 is built.

Similar to the first example embodiment, the fourth flow channel 4 mayhave a cut-out portion (not illustrated) on the outer circumferentialsurface of the stator 501 or an inner circumferential surface 6 of thehousing 141. When the stator 501 has a cut-out portion, the surface areaof the stator 501 which comes into contact with an oil can be increased.Therefore, the inside of the motor section 201 can be more efficientlycooled. In addition, when the stator 501 has a cut-out portion, or whenthe housing 141 has a cut-out portion, the flow rate of an oil flowingto the fourth flow channel 4 can be increased. Therefore, an oil canmore efficiently circulate.

In addition, similar to the first example embodiment, the stator 501 andthe rotor 402 may be integrally molded products formed of a resin. Whenthe stator 501 or the rotor 402 is an integrally molded product formedof a resin, the surface area of the stator or the rotor which comes intocontact with an oil is increased. Therefore, the inside of the motorsection 201 can be more efficiently cooled.

According to the present example embodiment, the pump apparatus 101 hasthe motor section 201 that has the shaft 41 rotatably supported aboutthe central axis J extending in the axial direction; and the pumpsection 300 that is positioned on one side of the motor section 201 inthe axial direction, is driven by the shaft 41 extending from the motorsection 201, suctions an oil, and delivers the oil to the motor section201. The motor section 201 has the rotor 402 rotating around the shaft41, the stator 501 disposed to face the rotor 402, the housing 141accommodating the rotor 402 and the stator 501, and the discharge port131c provided in the housing 141 to discharge an oil. The pump section300 has the pump rotor 351 attached to the shaft 41, the pump caseaccommodating the pump rotor 351, the suction port 321 c provided in thepump case to suction an oil, and the delivery port 311 c provided in thepump case to deliver an oil to the motor section 201. In the pumpapparatus 101, the suction port 321 c, the delivery port 311 c, and thedischarge port 131 c are disposed at positions different from each otherwhen viewed in the axial direction. The pump apparatus 101 has the firstflow channel 1 for suctioning an oil into the pump section 300 throughthe suction port 321 c of the pump section 300 using a negative pressurein the pump section 300, the second flow channel 2 for delivering an oilto the inside of the motor section 201 through the delivery port 311 cof the pump section 300 using pressurization of the pump section 300,the third flow channel 3 provided between the stator 501 and the rotor402, the fourth flow channel 4 provided between the stator 501 and thehousing 141, and the fifth flow channel 5 for discharging an oil insidethe motor section 201 through the discharge port 312 c.

According to the present example embodiment, an oil which has beensuctioned into the pump section 300 through the suction port 321 c dueto a negative pressure in the pump section 300 and has been delivered tothe motor section 201 through the delivery port 311 c due topressurization of the pump section 300 flows inside the motor section201. Accordingly, the oil cools the stator 501 and the rotor 402 at thesame time. In the present example embodiment, an oil which has beensuctioned into the pump section 300 is not divided into an oil to bedischarged to the external apparatus and an oil for cooling the motorsection 201, and an oil which has been suctioned into the pump section300 is delivered to the motor section 201. Therefore, cooling of thestator 501 and the rotor 402 can be realized at the same time withouthaving the pump efficiency being degraded. In addition, according to thepresent example embodiment, in the pump apparatus 101, the stator 501can be cooled from both the housing 141 side and the rotor 402 side byincluding the third flow channel 3 and the fourth flow channel 4.Therefore, the stator 501 can be efficiently cooled. That is, it ispossible to provide a structure having a high cooling effect for curbingtemperature rise in the motor section 201.

In the pump apparatus 101 of the present example embodiment, a casewhere the stator 501 is fixed to the bearing housing 630 has beendescribed. However, the constitution is not limited thereto. Forexample, even when the stator 501 of the pump apparatus 101 is fixed tothe housing 141, the present invention can be applied.

In addition, similar to the case of the first example embodiment, aconstitution having no delivery port 311 c can be employed, and thesecond flow channel 2 is positioned between the shaft 41 and the pumpbody 311. At this time, in the second flow channel 2, an oil passesthrough at least any part between the shaft 41 and the upper bearingmember 421, in the upper bearing member 421, and between the upperbearing member 421 and the pump body 311.

In addition, when the shaft 41 penetrates the bottom wall 131 a of thesecond housing 131 and protrudes to the rear side, a constitution havingno discharge port 131 c can be employed. In this case, the fifth flowchannel 5 is positioned between the shaft 41 and the bottom wall 131 aof the second housing 131. In the fifth flow channel 5, an oil passesthrough at least any part between the shaft 41 and the lower bearingmember 422, in the lower bearing member 422, and between the lowerbearing member 422 and a lower bearing holding portion 652 provided inthe bottom wall 131 a.

In addition, in the present example embodiment, a case where the motorsection 201 of the pump apparatus 101 has only the rotor 402 has beendescribed. However, the constitution is not limited thereto. Forexample, the motor section 201 may have two rotors. For example, tworotors may be attached to the shaft 41 at a predetermined interval inthe axial direction and the stator 501 may be disposed between the tworotors. The present invention can be applied to the foregoingconstitution having two rotors.

Hereinabove, example embodiments of the present invention have beendescribed. However, the present invention is not limited to theseexample embodiments, and various modifications and changes can be madewithin a range of the gist thereof.

While example embodiments of the present disclosure have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present disclosure. The scope of the presentdisclosure, therefore, is to be determined solely by the followingclaims.

1-23. (canceled)
 24. A pump apparatus comprising: a motor including ashaft rotatably supported about a central axis extending in an axialdirection; and a pump on one side of the motor in the axial direction,is driven by the shaft extending from the motor, suctions an oil, anddelivers the oil to the motor; wherein the motor section includes: arotor rotating around the shaft; a stator disposed to face the rotor; ahousing accommodating the rotor and the stator; and a discharge portprovided in the housing to discharge the oil; the pump includes: a pumprotor attached to the shaft; a pump case accommodating the pump rotor; asuction port provided in the pump case to suction the oil; and adelivery port provided in the pump case to deliver the oil to the motor;the suction port, the delivery port, and the discharge port are disposedat positions different from each other when viewed in the axialdirection; and the pump apparatus includes: a first flow channel tosuction the oil into the pump through the suction port of the pump usinga negative pressure in the pump; a second flow channel to deliver theoil to an inside of the motor through the delivery port of the pumpusing pressurization of the pump; a third flow channel provided betweenthe stator and the rotor; a fourth flow channel provided between thestator and the housing; and a fifth flow channel to discharge the oilinside the motor section through the discharge port.
 25. The pumpapparatus according to claim 24, wherein the pump case includes a pumpcover and a pump body; the pump body is open at both ends in the axialdirection to allow the shaft to pass therethrough; the pump cover blocksan opening of the pump body on one side in the axial direction; and thepump rotor rotates due to rotation of the shaft.
 26. The pump apparatusaccording to claim 25, wherein the suction port is provided in the pumpcover.
 27. The pump apparatus according to claim 25, wherein the suctionport is provided on a side surface of the pump body.
 28. The pumpapparatus according to claim 25, wherein the suction port is provided ina wall portion of the pump body extending to a pump side in the axialdirection.
 29. The pump apparatus according to claim 24, wherein thesuction port is connected to a negative pressure region inside the pump.30. The pump apparatus according to claim 25, wherein the delivery portis provided on a surface of the pump body facing the pump cover.
 31. Thepump apparatus according to claim 25, wherein the second flow channel islocated between the pump body and the shaft.
 32. The pump apparatusaccording to claim 31, wherein the pump includes a bearing between thepump body and the shaft; and in the bearing, one end of the bearing on aside of the pump in the axial direction is on a side of the motor of oneend of the pump body on the side of the pump.
 33. The pump apparatusaccording to claim 24, wherein when the pump apparatus is disposed suchthat the axial direction extends horizontally, the delivery port ispositioned below the shaft in a direction of gravity.
 34. The pumpapparatus according to claim 24, wherein the delivery port is connectedto a pressurization region inside the pump.
 35. The pump apparatusaccording to claim 24, wherein the suction port and the delivery portare disposed at positions different from each other in a circumferentialdirection with respect to the central axis.
 36. The pump apparatusaccording to claim 24, wherein when the pump apparatus is disposed suchthat the axial direction extends horizontally, the discharge port ispositioned above the shaft in a direction of gravity.
 37. The pumpapparatus according to claim 24, wherein the discharge port is providedin a bottom portion of the housing.
 38. The pump apparatus according toclaim 24, wherein the motor includes a bearing held in a bottom portionof the housing and rotatably supports the shaft; and the oil passesthrough the fifth flow channel between the shaft and the bearing. 39.The pump apparatus according to claim 24, wherein the discharge port isprovided in a side surface of the housing.
 40. The pump apparatusaccording to claim 39, wherein the discharge port is positioned betweenone end of the stator on a side opposite to the section in the axialdirection and a bottom portion of the housing.
 41. The pump apparatusaccording to claim 24, wherein a plurality of discharge ports areprovided in the housing.
 42. The pump apparatus according to claim 41,wherein the discharge ports are provided in a bottom portion and on aside surface of the housing.
 43. The pump apparatus according to claim24, wherein a cross-sectional area of the delivery port is smaller thana cross-sectional area of the discharge port.